GM ZZ4 Crate Engine - Repurposing

Breathe new life into an old short-block with a few aftermarket parts

1. Our starting point is this clean ZZ4 GM Performance Parts 350-inch short-block. At some point someone swiped all the parts off of it and left it languishing in a corner. Back when it was all together, this GM crate engine was rated at 355 hp and 405 lb-ft of torque. Not bad, but we’re pretty sure we can improve on those numbers without sacrificing street manners or breaking the bank.

These days, recycling is all the rage. Airplanes get ground up and turned into beer cans, which eventually get melted down and formed into some other widget we just can’t live without. In a way, hot rodding is one of the “greenest” hobbies out there. We take old, worn-out junk and rebuild it into functioning items. This is especially true of engines. Sometimes it’s an old crank that’s cleaned up and put to use again, or maybe it’s a discarded engine block left to gather dust in the back of a shop. Whatever it is, the whole concept of turning trash into treasure is what drives our hobby.

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The nexus for this story was an old short-block we found in the back of the shop. After doing a little sleuthing, we determined it was the remnants of a GM ZZ4 crate engine. We’re pretty sure that a lot of hot rodders have half-built engines lying about, so why not see what a few aftermarket parts could recycle these mills into.

In this case, the ZZ4 first hit the streets well over 10 years ago. Back then, 355 horsepower seemed like a much bigger number, and the price of gas actually was a much smaller one. So our plan is to up the power a bit by using a less expensive grade of gasoline. We also wanted to try out a few parts that have recently caught our attention. The first was a Thumpr cam from COMP. These hydraulic roller cams are ground and profiled to maximize the rough-idling characteristics without negatively impacting the power output or streetability of the engine. In other words, the hot rod sound we love without the hassle.

We also wanted to try out Summit’s new line of affordable aluminum heads. The cost of cylinder heads can quickly consume the lion’s share of any engine building budget, so finding some affordable choices that still make good power really helps in keeping the cost down. To make sure we did it right, we hauled all the parts over to JR Competition Engines in Escondido, California.

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GM ZZ4 Crate Engine - Repurposing

1. Our starting point is this clean ZZ4 GM Performance Parts 350-inch short-block. At some point someone swiped all the parts off of it and left it languishing in a corner. Back when it was all together, this GM crate engine was rated at 355 hp and 405 lb-ft of torque. Not bad, but we’re pretty sure we can improve on those numbers without sacrificing street manners or breaking the bank.

1. Our starting point is this clean ZZ4 GM Performance Parts 350-inch short-block. At some point someone swiped all the parts off of it and left it languishing in a corner. Back when it was all together, this GM crate engine was rated at 355 hp and 405 lb-ft of torque. Not bad, but we’re pretty sure we can improve on those numbers without sacrificing street manners or breaking the bank.

2. Since it had been sitting around for who knows how many years, JR Twedt, owner of JR Competition Engines, decided to do a quick teardown and inspection of the short-block. He found the GM parts, including the powdered metal rods, aluminum pistons, and forged crank, to all be in great condition.

3. For a camshaft, we ditched the factory 208/221 112 LSA camshaft for a COMP Thumpr stick (PN 08-600-8, $297). The Thumpr wasn’t crazy big (227/241 duration 107 LSA), but it will give the engine that lumpy hot rod sound we dig.

4. The GM timing chain was MIA so we picked up a nice COMP roller timing chain and gear set from Summit Racing (PN 3136, $72).

5. With the parts in place, JR was able to properly degree the cam. This often overlooked step is crucial if the engine is going to run to its full potential.

6. The roller system used this set of GM hydraulic lifters and a spider lifter retainer.

7. We then installed the Rattler Torsional Vibration Absorber from TCI. The Rattler is designed to absorb, rather than just dampen vibrations, and is SFI 18.1 certified.

8. When it came to heads, we had a choice to make. The GM heads that came with the ZZ4 engine had 58cc chambers, which worked the compression to right around 10.0:1, requiring 92-octane gas. Given today’s gas prices, we opted to go with Summit Racing’s 200cc street/strip aluminum heads (PN 162111, $1,050 pair). These feature 64cc chambers, which will drop the compression ratio to around 9.6:1, allowing us to run much less expensive 87-octane gas if we choose.

9. For just a grand, it’s really hard to beat these Summit-branded heads. They feature phosphorous bronze valveguides, ductile iron valve seats, and came fully assembled with 2.02-inch intake and 1.60-inch stainless steel exhaust valves. The heads also had screw-in rocker studs, guideplates, and 7-degree valve locks. To secure them to the block, we used a set of Fel-Pro head gaskets (PN 1003, $36 each) and a set of ARP stainless head bolts (PN 434-3601, $167). If you want to sacrifice a little bling and save a few bucks, you can get the bolts in black oxide for $77.

10. For rockers, we decided to roll with a set of COMP Ultra Gold's we had left over from a previous build (PN 19004-14, $308). On this engine we could have gotten away with a lesser rocker, but the Ultra Gold’s are rock solid, and being full-roller, they will free up a bit of power. This did mean we needed to swap out the 3⁄8-inch rocker studs that came with the Summit heads for some 7⁄16-inch versions.

11. It’s a street engine, so we opted to go the dual-plane route when choosing an intake. This Weiand Speed Warrior aluminum intake (PN 8501, $216) featured long, separated runners for improved bottom and mid-range power, plus the runner design won’t choke off the power in the higher rpm range (up to 6,000 rpm).

12. Now, when it comes to valve cover gaskets you can cheap out and go with standard cork, but we much prefer these Fel-Pro steel-core silicone pieces (PN 1628). They seal great, which equates to no leaks of oil or vacuum. They will also last nearly forever. Trust us, they are well worth the $50 investment.

13. To spark the fuel, we chose a ready-to-run MSD billet distributor (PN 8360, $280). With a vacuum advance, we will get better economy, which is even more important these days. The housing features an all-billet 6061-T6 aluminum design for superior accuracy, and an oversized steel shaft that is QPQ-coated for low friction. Sealed bearings at the top and bottom of the distributor make sure it all stays steady, which equates to accurate spark delivery at any rpm.

14. This engine belongs to Dick Kvamme over at Best of Show Coach Works in Escondido, California, and since they’re always willing to lend us a lift or spray a little paint, we asked the guys over at Eddie Motorsports (EMS) to whip up some special valve covers for the small-block. EMS can laser-etch any design you send them onto their valve covers, air cleaners, breathers, or other widgets for a fee based on the complexity of the design. Pricing starts at $30, and the logo we sent them ran about $50 for the pair, plus the cost of the valve covers.

15. To top off our engine, we went with Holley’s new Ultra Street Avenger carburetor (PN 86779HB, $549). At 770 cfm, it’s sized just right for our mill, and the electric choke will make it easy to live with on the street. The carb features ultra-lightweight aluminum construction along with billet metering blocks and base for more strength than cast pieces. It’s also easy to adjust and change the spring for the vacuum actuated secondaries.

16. We headed over to Westech Performance and strapped the newly revitalized ZZ4 engine to the Superflow dyno, filled the tank with pump gas, and fired it up. Once properly broken in, Westech’s carb guru, Steve Brule, started making pulls and performing adjustments. Over the course of a dozen pulls, he gradually added timing, installed a lighter spring for the vacuum secondaries, and swapped the jets around. On pull 13, we were rewarded with our best corrected numbers of 413 hp and 415 lb-ft of torque. That’s more power than the ZZ4 made stock, and we did it with less compression and on a lower octane gas than GM recommends. As for torque, the peak isn’t much higher than the ZZ4’s advertised number, but we really like the flat curve and the fact that it made over 370 lb-ft of torque way down at 3,000 rpm. If we didn’t mind upping the compression and running the more expensive swill, there was even more power to be had, but we still remember when a 400hp engine was enough to make us smile.

To build or buy is one of the most important questions to ask yourself when it comes to engines and there are many companies to choose from, that is why we have listed Chevy Crate Engine options from the expensive big-blocks to the budget minded small-blocks. - Super Chevy Magazine » Read More